Holiday Readings: Ancient Amputations, First Americans, Fossil Molluscs

Wishing my readers a very Happy New Year! I hope these readings will be to your liking.

1) Can ancient amputations tell us about the care systems of our ancestors? Paleoanthropologist John Hawks surveys the fossil record of ancient humans for signs of severed limbs due to trauma or disease. He also presents cases of limb loss in other primates and offers a perspective on what all this can tell us about past social systems. 

"Both humans and nonhuman primates show us that survival and life after extreme injuries happen under varied circumstances. Bioarchaeologists tend to highlight severe injuries, which stand out from the more subtle patterns of osteological signs of disease that can be understood only across large samples of skeletons. But such individual stories rarely yield unambiguous interpretations".

2) Finding the First Americans. Anthropologist Jennifer Raff brings together often conflicting genetic and archaeological data on this ever vexing and complicated question of how the Americas were populated. 

3) Finding Molluscs. This podcast (with transcript) is part of an excellent continuing series of earth science and paleontology podcasts by Mongabay India. In this episode, host Sahana Ghosh talks with paleoecologist Devapriya Chattopadhyay on her research on fossil molluscs. Dr. Chattopadhyay uses these creatures to track ancient environmental conditions and ecology. She also speaks on the urgent need for India to create a national fossil repository and museum which will help preserve our deep history for future generations.

Readings: Mars Geology, Human Diversity, India Rock Art

 A few interesting readings:

1) NASA's Mars Perseverence Rover is hard at work. It has an amazing collection of geochemical instruments which are probing the surface with the aim of categorizing the mineralogy and chemistry of surface materials. The hope is to pinpoint regions which could have hosted microbial life.

Signs of Life on Mars: NASA's Perseverance Rover Begins the Hunt 

2) How are Andaman Islanders closer to Swedes than to Africans?

Razib Khan explain in this informative essay on patterns of human diversity and what it tells us about human migrations and population admixture over the past 100,000 years.

Out of Africa's midlife crisis-on bottlenecks, crashes and what diversity really looks like: How are Andaman Islanders closer to Swedes than to Africans?

3) On the Aravalli ranges quartzite rock faces in the state of Haryana is art created as long as 20,000 years ago. The locals always knew about it, but the Archeological Survey has just begun studying it in detail. 28 ancient sites have been found. I hope all of them get protection immediately. Smithsonian Magazine has a summary describing these finds. The final photo of rock art in the article depicts mounted warriors. Are they mounted on donkeys/mules or horses? Curious to know what readers think. I am leaning towards them being donkeys or mules.

These Millennia-Old Cave Paintings May Be Among India’s Oldest. 

Mass Extinction, Peopling Of America, Tale Of The Horse

 Sharing some interesting items:

1) What was the impact of Deccan Volcanism on the end-Cretaceous mass extinction? Improved dating of the timing of volcanism shows that volcanism spanned the mass extinction. But what changes occurred to marine environments because of the outgassing wasn't well documented. A new study uses the oxygen isotope ratios in foraminifera shells to estimate ocean temperature changes before and after the mass extinction. The finding is that the oceans warmed well before the extinction but cooled back again. The warming event doesn't appear to correlate with marine extinctions. Rather the mass extinction coincides with evidence for a meteorite impact. 

Here is a figure from the paper on the estimated temperature changes collated using a variety of proxies:

Source: On impact and volcanism across the Cretaceous-Paleogene boundary

Joshua Sokol has written a good summary of the paper:

A Rapid End Strikes the Dinosaur Extinction Debate.

2) Anthropological geneticist Jennifer Raff has pieced together the genomic story of the peopling of the American continents in this really insightful article. Do read it!

Genomes Reveal Humanity’s Journey into the Americas.

3) And next, onwards to a bit of Indian history. A very interesting conversation between Live History India editor Mini Menon and author Yashaswini Chandra on Ms. Chandra's new book, The Tale of the Horse: A History of India on Horseback. Fascinating story of the horse trade from Central Asia into India and its assimilation as a war animal and into Indian society. 

The Tale of the Horse (video). 

Readings: Myanmar Geology, Holocene Human Populations, Indian Archaeology

Some interesting readings over the past few weeks:

1) Myanmar Geology- Oblique convergence, where plates converge or collide at an angle, has produced some stunning geological features in Myanmar. Lon Abbot and Terri Cook sail down the Irrawaddy River describing vestiges of volcanic arcs, strike slip faults, en echelon sedimentary basins, and fold mountains, with a fair bit thrown in about the architecture and cultural history of the country.

Sailing Through A Subduction Zone.

2) Genetics And Human Evolution- Razib Khan compiles a nice list of the many aspects of human evolution and especially Holocene population history that has been brought out by recent work in genomics and ancient DNA.

What I'm Thankful To Know About Genetics And History In 2020.

3) Indian Archaeology- A sort of historiography of the field of Indian archaeology from Colonial times to today. Dilip Menon writes about the push and pull of ideas of conquest, politics, and nationalism that influence Indian archaeology research and narratives.

How Archaeology Has Shaped India’s Imagination Of Itself. 

Readings: India Dams, Geology Videos, Parsis in India

 Sharing some readings.

1) Neeraj Wagholikar, Parineeta Dandekar and Himanshu Thakkar weigh in on the dam building epidemic that is afflicting India. These three experts cover issues of environmental governance, destruction of fisheries and livelihoods, and a perspective on their irrigation potential and economic logic.

The deep political drive to push through permissions to build dams is best highlighted by an example of a malign recommendation in a report of the Parliamentary Standing Committee on energy published in January 2019. It seems to view in favor Himachal Pradesh's suggestion to the committee to help declare large hydropower projects as linear projects, thus enabling them to bypass Gram Sabha consent. The statement reads, “If it is done, then, to a large extent, the problem of FRA, which the Secretary also mentioned, will get resolved because the stringent provisions of FRA will get diluted. It is not our purpose to subvert them. Our only purpose is to get them more liberalised.” 

FRA is the Forest Rights Act which gives local forest dwellers a say in the site selection of infrastructure projects. 

Makes you despair and shake in anger, doesn't it?

India, Dammed.

2) Geology fans! I highly recommend Rice University Professor Cin-Ty Lee's YouTube Channel. He has a very informative collection of short videos on rocks and minerals and geologic processes. 

Here is one of my favorites.. Isostacy and what controls the elevation of mountains?

Email subscribers who can't see the embedded video, can view it here - Elevation of Mountains.

3) Like Sugar in Milk.. was the memorable assurance given by the Zoroastrian refugees to the King of Gujarat. We will assimilate in Indian society. And they have in many ways, while maintaining a distinct identity. 

What does genetics tell us? Fine post by Razib Khan.

Endogamy and Assimilation. Parsis in India.

No Population Continuity Between Pre Toba And Extant Humans In India

A few years ago stone tools were discovered in the Jurreru Valley region of Kurnool district, South India, in sediment stratigraphically below a volcanic ash layer dated to around seventy four thousand years ago. This was the deposit of the famous Toba eruption. Michael Petraglia, an archaeologist based at the University of Oxford, England, suggested that these tools were made by Homo sapiens. This would mean that our species had first migrated out of Africa and into India perhaps as early as hundred thousand years during the Marine Isotope Stage 5 interglacial phase when ecological corridors may have opened up between Africa, Arabia and the Indian subcontinent. This is much before the more commonly accepted dates of around fifty to sixty thousands years ago. Other scientists objected and argued that the tools were made by an earlier species of archaic Homo, perhaps descendants of Homo erectus who had migrated to India more than a million years ago. The various theories of the dispersal of Homo sapiens from Africa has been summarized well recently in an article by Huw. S Groucutt and colleagues.

The earliest unequivocal skeletal evidence of the presence of anatomically modern humans in the Indian subcontinent comes from Sri Lanka where these remains have been dated to be around thirty five thousand years old. They represent humans from the later wave of the out of Africa migrations.

A related question was left dangling. If these tools were made by people from an earlier migration of Homo sapiens, then is there population continuity between those older migrants and living Indians?  Did later migrants mix with the earlier inhabitants or did the earlier human populations go extinct without leaving a genetic legacy in us.

There were other hints of the presence of an older wave of Homo sapiens migration into India. The Indian Early to Mid Pleistocene hominin skeletal record is quite poor with examples only from the Narmada Valley at Hathnora and Nethankari . At the latter site, a humerus interpreted to represent a "short and stocky" early Homo sapiens has been found associated with delicate bone implements. The remains may be around seventy five thousand years old or even older. At Hathnora, two clavicles and a partial 9th rib was recovered from a layer of fluvial sediment. The materials are thought to be about one hundred and fifty thousand years old and have been interpreted to be an archaic Homo sapiens. What is the margin of error on these dates? Could they be a little younger and represent the early MIS 5 phase migration from Africa around one hundred to one hundred and twenty five thousand years ago? This population seems to have persisted for several tens of thousands of  years as is evidenced by the younger remains at Nethankari.

There is evidence in the form of tools  as well as skeletal material found in Israel, the Arabian Peninsula and China, that indicate that anatomically modern humans did migrate out of Africa as early as a hundred thousand years ago.  A series of DNA studies of global human populations published a few days ago seems to say that people from these earlier migrations died out without contributing ancestry to extant humans. The three studies say that all non-African humans have descended from a single wave of migration  that took place between fifty thousand and eighty thousand years ago.

The scientists, A.R. Sankhyan and colleagues, working on the remains of the short and stocky Narmada Valley hominin had suggested that this population may have contributed ancestry to later short bodied people of South Asia, for example the Andamanese tribes. This scenario now looks untenable. These older (putative) Homo sapiens  in India and elsewhere died out without leaving a genetic trace.

The exception to these findings seems to be in Papua New Guinea. One study finds that 2% of the genome of present day Papuans originated from an earlier expansion  of modern humans out of Africa.

Carl Zimmer has written a good summary of the results.

Here are the links to the papers -

1)  Genomic analyses inform on migration events during the peopling of Eurasia
2) The Simons Genome Diversity Project: 300 genomes from 142 diverse populations
3) A genomic history of Aboriginal Australia

Why didn't people from the two separate waves of modern human migrations mate? The answer likely is because they never met. These older Homo sapiens populations went extinct before the new settlers came. I say this because recent genetic work has shown that one almost inevitable outcome of the meeting of two peoples, however different they may be, is sexual intercourse. When modern humans left Africa fifty-sixty thousand years ago they met and interbreed with Neanderthals and Denisovans, two older hominin groups whose ancestors had left Africa about half a million years ago.

Consider also what happened much later in the Holocene. The end of last ice age and the advent of agriculture saw population growth and the migration and mixing of people. Many of these populations had diverged and remained relatively isolated for more than twenty thousand years, accumulating significant cultural, linguistic and physical difference between them. Yet, the result of the meeting of these people was mostly not the genetic disappearance of one group, but admixture and the formation of modern groups with multiple streams of ancestry.

Today's Europeans contain ancestry from three different groups. A small fraction from earlier resident hunter gatherers and the more substantial fraction from Near East farmers and from Central Asian steppe pastoralists. When Europeans began colonizing the Americas, the native populations suffered immensely from disease and subjugation. But there was also genetic admixture. Native Americans today, both from South and North Americas, contain a noticeable amount of  European and African ancestry.

In the Indian context multiple events of mixing in the Holocene took place between residents (the Ancestral South Indians) and migrants from the Eurasian regions (the Ancestral North Indians). Additions layers of ancestry to the Indian melting pot (but common more in the eastern parts of the country) were contributed by migration of the Tibeto-Burman and the Austroasiatic people from the north east.

Why did the older group of Homo sapiens go extinct? According to Dr Pagani, one of the scientists involved in the first study I listed above “They may have not been technologically advanced, living in small groups,”... “Maybe it was easy for a major later wave that was more successful to wipe them out.”

Or as I suggested, they went extinct before the new settlers arrived. Living in small isolated populations leaves people vulnerable to disease and environmental catastrophe. One such event could have been the Toba eruption which had considerable environmental impact in South Asia. Could that have played a role in the demise of older Homo sapiens groups in Asia?  It would be interesting to see if there is archaeological evidence of an overlap between the two groups of modern humans anywhere.

Mallick, S., Li, H., Lipson, M., Mathieson, I., Gymrek, M., Racimo, F., Zhao, M., Chennagiri, N., Nordenfelt, S., Tandon, A., Skoglund, P., Lazaridis, I., Sankararaman, S., Fu, Q., Rohland, N., Renaud, G., Erlich, Y., Willems, T., Gallo, C., Spence, J., Song, Y., Poletti, G., Balloux, F., van Driem, G., de Knijff, P., Romero, I., Jha, A., Behar, D., Bravi, C., Capelli, C., Hervig, T., Moreno-Estrada, A., Posukh, O., Balanovska, E., Balanovsky, O., Karachanak-Yankova, S., Sahakyan, H., Toncheva, D., Yepiskoposyan, L., Tyler-Smith, C., Xue, Y., Abdullah, M., Ruiz-Linares, A., Beall, C., Di Rienzo, A., Jeong, C., Starikovskaya, E., Metspalu, E., Parik, J., Villems, R., Henn, B., Hodoglugil, U., Mahley, R., Sajantila, A., Stamatoyannopoulos, G., Wee, J., Khusainova, R., Khusnutdinova, E., Litvinov, S., Ayodo, G., Comas, D., Hammer, M., Kivisild, T., Klitz, W., Winkler, C., Labuda, D., Bamshad, M., Jorde, L., Tishkoff, S., Watkins, W., Metspalu, M., Dryomov, S., Sukernik, R., Singh, L., Thangaraj, K., Pääbo, S., Kelso, J., Patterson, N., & Reich, D. (2016). The Simons Genome Diversity Project: 300 genomes from 142 diverse populations Nature DOI: 10.1038/nature18964

Groucutt, H., Petraglia, M., Bailey, G., Scerri, E., Parton, A., Clark-Balzan, L., Jennings, R., Lewis, L., Blinkhorn, J., Drake, N., Breeze, P., Inglis, R., Devès, M., Meredith-Williams, M., Boivin, N., Thomas, M., & Scally, A. (2015).               Rethinking the dispersal of
             
              out of Africa
             Evolutionary Anthropology: Issues, News, and Reviews, 24 (4), 149-164 DOI: 10.1002/evan.21455

Peopling Of The Americas- Rapid Settlement And Substantial Lineage Extinction Upon European Contact

Here is the full paper : Ancient mitochondrial DNA provides high-resolution time scale of the peopling of the Americas

The exact timing, route, and process of the initial peopling of the Americas remains uncertain despite much research. Archaeological evidence indicates the presence of humans as far as southern Chile by 14.6 thousand years ago (ka), shortly after the Pleistocene ice sheets blocking access from eastern Beringia began to retreat. Genetic estimates of the timing and route of entry have been constrained by the lack of suitable calibration points and low genetic diversity of Native Americans. We sequenced 92 whole mitochondrial genomes from pre-Columbian South American skeletons dating from 8.6 to 0.5 ka, allowing a detailed, temporally calibrated reconstruction of the peopling of the Americas in a Bayesian coalescent analysis. The data suggest that a small population entered the Americas via a coastal route around 16.0 ka, following previous isolation in eastern Beringia for ~2.4 to 9 thousand years after separation from eastern Siberian populations. Following a rapid movement throughout the Americas, limited gene flow in South America resulted in a marked phylogeographic structure of populations, which persisted through time. All of the ancient mitochondrial lineages detected in this study were absent from modern data sets, suggesting a high extinction rate. To investigate this further, we applied a novel principal components multiple logistic regression test to Bayesian serial coalescent simulations. The analysis supported a scenario in which European colonization caused a substantial loss of pre-Columbian lineages.

Several points of interest come to mind.

a) Separation with Siberian common ancestors took place about 24 thousand years ago, followed by a long period of isolation in Beringia (see Fig.).

The founder lineages then settled the America's quite rapidly beginning around 16 thousand years. Sites in Chile show human habitation by 14 thousand years.

b) The much talked about Clovis culture were not the first Americans.

c) There was a demographic collapse among the Native American populations. Charles Mann's 1491 gives quite a sweeping account of both native and Spanish eye witness accounts of the wiping out of entire tribes and communities due to Old World diseases. This paper backs that up using genetics. A comparison of ancient DNA with present day Native American DNA shows that extensive extinction of mitochondrial lineages took place.  In plain language, entire tribes were wiped out to be replaced  much later by natives migrating from some other place, although the authors caution some of the discontinuity of lineages could be because  modern diversity may have been undersampled.  The data for ancient DNA comes principally from the western coast of South America which had large Native American population centers.   Lowland populations went extinct more. Highland populations were less affected. Perhaps population contact was more in the lowlands and diseases like malaria more prevalent in the warmer climes?

5300 Year Old Iceman's Bacteria Genome Does Not Support Out Of India Theory

The genome of bacterium Helicobacter pylori found in  the stomach of the 5300 year old European mummy named the "Iceman" shows close similarity with Helicobacter pylori strains found in the gut of north Indians. This finding published in Science has been used as evidence to support the Out of India theory, which proposes that the Aryans and the Indo-European language family originated in India. One branch of it spread into Europe, diverging into various IE languages, while the branch which remained in India became the common  ancestor of Iranian and Sanskrit. A later migration into Iran founded the Iranian branch of the IE family.

Here is a tweet by Subhash Kak, one of the proponents of the Out of India theory.

He and others who use this finding of the bacterial genome to support this scenario are wrong.

Here's why.

Their scenario requires the European strain of Helicobacter pylori to have been derived from the Indian strain. That means people from India migrated  into Europe in the Neolithic-Early Bronze Age around five to six thousand years ago carrying with them the Indian bacterial strain which then evolved into the European variety found in the Iceman. This interpretation is demonstrably wrong. The analysis of the bacterial genomes clearly shows that the Indian strain shares ancestry with the European strain

" The resulting linked co-ancestry matrix (Fig. 4) showed that the ancient H. pylori genome shares high levels of ancestry with Indian hpAsia2 strains (Fig. 4, green boxes), but even higher co-ancestry with most European hpEurope strains".....

... "Furthermore, our co-ancestry results indicate that the Iceman’s strain belonged to a prehistoric European branch of hpAsia2 that is different from the modern hpAsia2 population from northern India".

In plain English what this mean is that the European strain has not evolved directly from the Indian strain.  Rather, the European strain and the Indian strain share an Asian common ancestor. This is clearly seen in the phylogeny (evolutionary relationship) presented in the supplementary materials of the  paper (page 50 of 88). See the image below.

Source: Supplementary Materials Maixner et al. 2016

The red arrow points to the common ancestor of the Iceman and Indian strains. The Iceman's strain and the Indian strain are sister lineages. The European strain is not derived from the Indian strain. The most sensible explanation of this finding is that from a common Asian source in the Anatolian / Near East region this bacteria spread into Europe and into India with the Neolithic expansion of farmers. It then diverged into the respective strains seen in the Iceman and in extant Indians. In Europe, this Asian derived strain then mixed with an African variety due to a migration in more recent times.

No evidence can be  found for a bronze age Out of India migration of people and languages from this study of the Iceman's bacterial genome.

Agriculture Changed Us

.. and I don't mean just culturally,  but biologically as well.

Carl Zimmer in the New York Times summarizes recent results from a wide ranging study which incorporates the genetics of extant as well as ancient Europeans. The study found evidence for several instance of natural selection altering height, digestion, skin color and our immune system.

from the article:

Previous studies had suggested that Europeans became better able to digest milk once they began raising cattle. Dr. Reich and his colleagues confirmed that LCT, a gene that aids milk digestion, did experience intense natural selection, rapidly becoming more common in ancient Europeans. But it didn’t happen when farming began in Europe, as had been supposed. The earliest sign of this change, it turns out, dates back only 4,000 years.

While agriculture brought benefits like a new supply of protein in milk, it also created risks. Early European farmers who depended mainly on wheat and other crops risked getting low doses of important nutrients.

So a gene called SLC22A4 proved advantageous as soon as Europeans started to farm, Dr. Reich and his colleagues found. It encodes a protein on the surface of cells that draws in an amino acid called ergothioneine. Wheat and other crops have low levels of ergothioneine, and the new variant increases its absorption. That would have increased the chances of survival among the farmers who had the gene.

People who are followers of the going back to a hunter gatherer Paleolithic diet fad, take note. Our digestive arsenal and our micro-biomes have responded to a different agricultural food combination. Human evolution did not freeze with the coming of the ice age. Agriculture and animal  domestication have pushed evolution into changing our DNA.

For a more detailed treatment on human evolution over the Holocene, I recommend strongly Gregory Cochran and Henry Harpending's book - The 10,000 Year Explosion: How Civilization Accelerated Human Evolution.

Harappa DNA- What Could It Tell Us About Holocene Peopling Of India

Hindustan Times carried a report a few days back on the recovery of DNA from Harappa age skeletons at Rakhigarhi village in Haryana.

What could ancient DNA tell us about the Holocene population composition of  India?

Background:

Recent genetic studies of  Indian populations  shows that Indians are a admixture of two ancient populations, the Ancestral South Indians (ASI) and  the Ancestral  North Indians (ANI). The general understanding is  that ASI has been resident  in India  since the Pleistocene, while ANI ancestry -which is related to Central and West Eurasians- was introduced in India  at various times during the Holocene. ANI and ASI are deeply divergent populations having separated from each other as early as 30 thousand to 40 thousand years ago.

ANI ancestry in Indian populations decreases along a north to south cline and from upper caste to lower caste.  Indo-European speakers have a larger component of  ANI ancestry than Dravidian speakers with North Indian upper castes showing the highest ANI ancestry.

Scenarios:

Lets assume that a representative sample of Harappa society is eventually collected. What could Harappan DNA tell us?

1) There is an absence of ANI in Harappa DNA. Harappans are unmixed ASI. This would indicate that Harappans were not Vedic Aryans. It will also have implications on how farming was introduced to the Indus valley.

2) Harappans have some ANI ancestry i.e they are a mix of ANI and ASI . This would not automatically mean that the ANI ancestry was contributed by Vedic Aryans. ANI is likely a fairly diverse group i.e. different groups of ANI after separating from West Eurasians may have  migrated into South Asia at different times in the Holocene. There is a possibility that ANI ancestry in Harappans reflects the migration of farmers (Dravidian speakers?)  from West Eurasia in the earlier part of Holocene. Moorjani et al's study indicates waves of admixture of ANI and ASI,  with middle and upper castes showing multiple layers of ANI ancestry and northern Indo European language groups shows younger admixtures dates than southern Dravidian speaking groups. These have been dated to a late and post Harappan period, although the authors say that their methods may have missed earlier admixture events. I am predicting that any ANI component in Harappans will be taken by many people as confirmation that the Vedic Aryans built the Harappan civilization.

3) Harappans have some ANI ancestry with markers suggestive of Indo-Aryan people ; One example could be the proposed West Eurasian origin -13910 C>T mutation for lactase persistence which in India  shows a northwest to southeast declining pattern. This would favor the scenario that the Vedic Aryans were a part of the Harappan civilization.  And there could be other markers typical to Indo-Aryans. Needless to say, such a finding will upset linguistic reconstructions of Indo-Aryan origins (proto-Sanskrit) thought to be not earlier than 2000 B.C. 

4) Harappans are entirely ANI. This would mean that ANI co-existed alongside ASI in the Indian subcontinent but remained genetically distinct for thousands for years until admixture in late/post Harappan times.

5) Update: November 21 2015- [ Harappans are an ASI-Austro Asiatic mix, likely speaking a Munda related language. This is a wild card entry and I am basing it on a linguistic hypothesis that there are loans words indicative of a northwest India geography in the early parts of the Rig-Ved that have phonetic similarities to Munda languages. This language substrate has been termed "Para-Munda" as it occurs really on the western most fringe of the occurrence of Munda language distribution in India, and based on its linguistic properties seems to be an early branch of the Austro-Asiatic language family.  This suggests that Indo-Aryans came in contact with resident Austro Asiatic language speakers in the Greater Punjab and Gangetic plains. Genetic work on Austro Asiatic language communities suggest a somewhat later entry (~ 2300 B.C) into East India from a Laos homeland, but Harappans just might represent an early wave of migrants from the east.]

We may get clear cut answers only when we can resolve with confidence the different layers of ANI ancestry.

I'm leaning towards Scenario (2). 

Theories Of Dispersal Of Homo Sapiens From Africa

Huw S. Groucutt and colleagues in Evolutionary Anthropology lay out the evolving story of the dispersal of Homo sapiens from Africa. The review brings together fossil, genetic  and archaeological data which now strongly leans towards a scenario of multiple migrations of Homo sapiens out of Africa beginning more  than hundred thousand years ago. These migrations followed ecological  windows of opportunity.  Interglacial phases resulted in wetter climate in the Levant and Arabia and may have made viable migration routes following either coastal contours or more interior passages towards the rest of Europe and Asia.

An Excerpt:

A variety of dispersal models (Table 1) address the period between the widely accepted African origin of Homo sapiens by around 200-150 ka and the arrival of our species at the margins of the Old World, including Australia, Siberia, and northwest Europe, by 50-40 ka.1–4 The evolutionary, demographic, and cultural processes between these milestones remain unclear, but a variety of recent studies add important new data.Whereas earlier models focused on assessing the geographical origins of our species based on fossil data, more recent approaches seek to combine fossil, genetic, archeological, and paleoenvironmental data to illuminate the nuances of dispersal into Asia (Table 1). These models emphasize different hypotheses concerning factors such as when dispersals began, how many occurred and which routes were followed. Recent models have largely fallen into two broad categories, emphasizing Marine Isotope  Stage (MIS) 5 (early onset dispersal model) or post-MIS 5 (late dispersal model) time frames (Table 1). This, however, is not a rigid dichotomy. For example, models proposing an early onset to dispersal are consistent with subsequent post-MIS 5 dispersals having also played an important role in patterns of human diversity.

The map below shows the distribution of Middle Paleolithic sites plotted on a modeled precipitation map of the last interglacial (MIS 5). The abundance of sites in the interior of Arabia speaks against a strictly coastal migration route into India. The interior of Arabia during humid phases would have been a mix of grasslands and riparian corridors offering potential dispersal routes into India and the rest of Asia.

Source: Huw S. Groucutt et. al. 2015

What is the Indian context?  The generally accepted earliest  modern Homo sapiens skeletal record in South Asia are ~35 k old fossils in Sri Lanka. But the tool record indicates presence of modern humans in India much before that. This review suggests that the totality of the tool records favors the theory that Homo sapiens may have entered India during MIS 5 more than a hundred thousand years ago, followed by additional  migrations beginning around fifty thousand years ago. Groucutt et. al. mention that future fossil discoveries from South Asia have the potential to transform ideas about the dispersal of Homo.

As of date the skeletal record of Homo in India consists of just a few fossils . Research by A.R.  Sankhyan and colleagues show that all of these have been found in the Narmada valley at Hathnora and a few km away at Netankheri . At Hathnora, hominin fossils occur in fluvial conglomerate and sand layer. One is a partially preserved calvarium and has been identified as a "robust" late Homo erectus or an archaic Homo sapien. Its cranial capacity is estimated to be 1200 cc to 1400 cc putting in the range of modern humans. It is associated with a collection of heavy duty large flake Acheulian hand axes and cleavers and chopping tools. The other fossil find at Hathnora consists of two clavicles and a partial 9th rib, interpreted to be belonging to a separate population of "short and stocky" archaic Homo sapiens associated with smaller Middle Paleolithic implements.  The cranium has been dated to the Middle Pleistocene ~ 250 k, while the clavicles and 9th rib appear to be younger with an estimated date to be ~150K range. A change in the ecology of this region is seen in the younger deposits based on the faunal content. The large flake tool industry disappears at this point in time . This has been interpreted to mean a migration of the larger robust archaic hominin away from this area based on appearance on this tool typology further north of this region and as far southeastwards to the Bastar region of Bihar.

At Netankheri, a partial femur and a humerus have been found. The femur occupies the same stratigraphic level as the Hathnora calvarium  and has been interpreted as belonging to late Homo erectus -archaic Homo sapien. The humerus though is of the "short and stocky" morphology and interpreted to represent an early modern Homo sapiens. Delicate bone implements have been found along with this fossil.  It is thought to be much younger, dated to be around 75 k, based on its stratigraphic position just below the Baneta Formation which contains Younger Toba Ash layers (ash deposits of the Toba eruption). The researchers interpret this to mean evolution from an archaic to a modern form, population continuity and continuous occupation of this area by this morphologically distinct hominin through the Middle and Late Pleistocene.

In summary, the skeletal and tool record points to presence of two culturally and physically distinct archaic hominin populations occupying the Narmada valley in the Middle Pleistocene. The tool record shows that Homo has been present in India for more than a million years and these physically distinct Middle Pleistocene hominins may be indicating the evolution of distinct hominin lineages in India. Or, was this population differentiation and morphological evolution inherited from an older African population structure, representing separate Middle Pleistocene migration episodes? And how they fit into the broader story of modern Homo sapiens dispersal and occupation of India remains to be worked out.

What is the margin of error on the 150 k date of the "short and stocky" hominin. Could they be younger and represent the early MIS 5 dispersal from Africa ( 100-125 K)?  Of interest are the ~35 K old Homo sapiens fossils from Sri Lanka which are physically distinct from the Netankheri "short and stocky" population. This points to another more recent (MIS 3) migration from Africa. Did these recent arrivals interbreed with the resident archaic hominins?  More fossils from South Asia are needed to fill in these gaps in our understanding of hominin evolution in India.  The authors of the Narmada hominins paper suggest that the "short and stocky" population may have contributed ancestry to later short bodied  populations of South Asia including the pygmies. Certainly, recent genetic work shows interbreeding between modern humans and other differentiated hominins like Neanderthals and Denisovans in Europe and East Asia respectively. Perhaps the Indian story is also one of assimilation of the earlier hominin populations with later human entrants.

I Hereby Bequeath You My Dog

Nicholas Wade writes about the possible locale of the earliest dog domestication and its impact on human societies:

Dog domestication and human settlement occurred at the same time, some 15,000 years ago, raising the possibility that dogs may have had a complex impact on the structure of human society. Dogs could have been the sentries that let hunter gatherers settle without fear of surprise attack. They may also have been the first major item of inherited wealth, preceding cattle, and so could have laid the foundations for the gradations of wealth and social hierarchy that differentiated settled groups from the egalitarianism of their hunter-gatherer predecessors. Notions of inheritance and ownership, Dr. Driscoll said, may have been prompted by the first dogs to permeate human society, laying an unexpected track from wolf to wealth.

Figure below (see link for explanation) depicts the genetic relationships between dog breeds to wolves.

Close proximity to animals and its impact on both biological and cultural evolution of humans is increasingly being appreciated and studied. In a sense domestication goes both ways...e.g. was inter-tribe /clan/family violence moderated by the presence of dogs protecting settlements?

Here is a link to the paper in Nature and if you want to listen to one of the lead scientists Robert K. Wayne I dug out this old talk on NPR on dog evolution and domestication. Its worth a listen.